Browsing by Author "Aura, Christopher Mulanda"

Now showing 1 - 4 of 4
  • Publication
    Publication
    Application of phytoplankton community structure for ranking the major riverine catchments influencing the pollution status of a lake basin
    (Wiley, 2020-02-18) Aura, Christopher Mulanda; Odoli, Cyprian; Nyamweya, Chrisphine S.; Njiru, James M.; Musa, Safina; Miruka, Jared Babu; Owili, Monica Ochieng; Omondi, Reuben; Raburu, Phillip; Manyala, Julius; Mwamburi, Job; Ogari, Zachary; Mbaru, Emmanuel K.
    The present study demonstrates the application of a multi‑metric Phytoplankton Index of Biotic Integrity (PIBI) approach for ranking of major river catchments in the Kenyan part of Lake Victoria on the basis of their pollution status. The index utilizes water quality and zooplankton data, phytoplankton diversity, abundance and attributes, as well as literature information. The rivers were sampled from 2016 to 2018 during the wet season (March) and dry season (July). The separation power of the Mann–Whitney U test (p < .05) qualified eight discriminant metrics for phytoplankton samples into a scoring system of 1, 3 and 5, based on high, fair and slight deviation from the best site, respectively, in development of the final PIBI. The Kuja and Sondu‑Miriu rivers had the highest PIBI, signifying least pollution influence on the lake. In contrast, the Yala and Nzoia rivers exhibited the lowest PIBI, representing the catchments with a higher pollution influence on the lake. The fair to poor integrity classes for the major river catchments in the region signified a deteriorating lakescape. The present study presents the preliminary results of using phytoplankton metrics for development of the Index of Biotic Integrity (IBI) approach in the region as a decision‑making support tool for the effective management and sustainable use of water resources in the lake basin.
  • Publication
    Publication
    Ecological integrity of a medium-sized river of a lake basin towards ecosystem health management
    (Wiley, 2023-10-13) Osure, George Owiti; Aura, Christopher Mulanda; Getabu, Albert; Omondi, Reuben; Basweti, Evans
    This study demonstrates the use of a multi-metric Fish Index of Biotic Integrity (FIBI) for assessment of ecological health of a medium-sized river, under a gradient of human disturbances in the Kenyan side of the Lake Victoria Basin (LVB). Development of the index is based on water quality, river habitat quality and fish community attributes. The river was sampled from 2019 to 2020 during wet and dry seasons of the year at nine selected sites along its length based on the level of human disturbance. A total of nine metrics representing the structural and functional organization of fish communities were qualified using the separation power of Mann–Whitney U test (p < .05). Metric values at unimpaired, intermediate, impaired and no-fish sites were used to establish the scoring criteria using inter-quartile ranges. A 1, 3, 5 scoring system representing high, fair and slight deviation from the best site, respectively, was used in the final FIBI development. River mouth station had the highest FIBI score of 43, with extensive natural riparian buffer vegetation (>20 m) and 18 fish species implying least human disturbance. The midstream section had intermediate FIBI scores of 34–36, with wide natural riparian buffer vegetation (10–20 m) and 6–9 fish species that represented moderate human disturbance. The upstream section had the least FIBI score of 0, with no fish and narrow riparian buffer vegetation (<5 m) that indicated notable degradation. This study presents the preliminary results of using fish and habitat metrics for development of an Index of Biotic Integrity (IBI) for a medium-sized river in a lake basin, as a decision-making support tool for effective management and conservation of water resources. The study recommends restoration of river habitat quality for improved ecological integrity of rivers in the Lake Victoria Basin.
  • Publication
    Publication
    Survival and avoidance response of the freshwater gastropod Melanoides tuberculatus (Muller) to different concentrations of tobacco waste
    (Aquaculture Research, 2012) Ogello, Erick Ochieng; Omondi, Reuben; Opiyo, Mary A.; Charo‐Karisa, Harrison; Munguti, Jonathan; Aura, Christopher Mulanda
    The Gastropod Melanoides tuberculatus plays a significant role in hampering fish larval production in earthen ponds. This study investigated use of tobacco waste to assess behavioural and survival responses of M. tuberculatus at different concentrations of tobacco waste solution of 0.25, 0.5, 0.75, 1.0, 1.25, 1.5, 1.75 and 2 g L−1. Mean escape time varied significantly among concentrations (P < 0.05). Escape time decreased in 1‐, 2‐ and 3‐day‐old solutions. Percentage survival decreased significantly with increasing concentrations of tobacco waste solution and exposure time (P < 0.05). Concentrations of 1.75 g L−1 and 2.0 g L−1 had high hazard ratios and low survival rates of gastropods and were the most effective in eradication of M. tuberculatus, hence recommended dose for preparing ponds for stocking. We conclude that tobacco waste solution can be used for control of M. tuberculatus.
  • Publication
    Publication
    Survival and avoidance response of the freshwater gastropod Melanoides tuberculatus (Muller) to different concentrations of tobacco waste
    (Wiley, 2012-09-13) Ogello, Erick Ochieng; Omondi, Reuben; Opiyo, Mary A.; Charo-Karisa, Harrison; Munguti, Jonathan; Aura, Christopher Mulanda
    The Gastropod Melanoides tuberculatus plays a significant role in hampering fish larval production in earthen ponds. This study investigated use of tobacco waste to assess behavioural and survival responses of M. tuberculatus at different concentrations of tobacco waste solution of 0.25, 0.5, 0.75, 1.0, 1.25, 1.5, 1.75 and 2 g L−1. Mean escape time varied significantly among concentrations (P < 0.05). Escape time decreased in 1-, 2- and 3-day-old solutions. Percentage survival decreased significantly with increasing concentrations of tobacco waste solution and exposure time (P < 0.05). Concentrations of 1.75 g L−1 and 2.0 g L−1 had high hazard ratios and low survival rates of gastropods and were the most effective in eradication of M. tuberculatus, hence recommended dose for preparing ponds for stocking. We conclude that tobacco waste solution can be used for control of M. tuberculatus.